Combine the roma tomatoes, garlic, onions and olive oil in a large baking pan. Sprinkle some sea salt and roast it in the oven at 200 degrees C for about 15 minutes or until all the vegetables are slightly charred.When all the vegetables are cool enough to handle, coarsely chop the tomatoes and onions. Finely chop the garlic and chipotle pepper. Then add the ground coriander, cumin, lime juice, fresh cilantro and some sea salt to taste. Serve the roasted tomato salsa at room temperature.